Electrical automatic fire alarm



Aug. 3Q, 1932- T. s. DIXON ETAL ELECTRICAL AUTOMATIC FIRE ALARM 5 Sheets-Sheet 1 Filed D69. 1, 1928 //////////////////l%fl////////// I INVE/VTQAS. Tfiom'as 5. F 3 W677i; Sim @9070. M,

Aug. 30, 1932. -r. s. DIXON ETAL ELECTRICAL AUTOMATIC FIRE ALARM s Sheets-Sheet 2 Filed Dec. 1. 1928 Aug. 30, 1932. T. s. DIXON ETAL ELECTRICAL AUTOMATIC FIRE ALARM Filed D66. 1. 1928 3 Sheets-Sheet 3 l/VVE/VTORS.

Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE.

THOMAS STOHEB DIXON AIVD ALBERT EDWARD SIMPSON, OF CHRISTCHURCH, NEW ZEALAND, ASSIGNORS TO THE VIGILALNT AUTOMATIC FIRE ALAItM COMPAQ LY LIM- ITED, OI CHRISTCHURCH, iNEW ZEALAND, A CORPORATION OF NEW ZEALANIY ELECTRICAL AUTOMATIC FIRE ALARM Application filed December 1, 1928, Serial No. 323,083, and in New zealand December 14, 1927.

This invention relates to fire alarm systems in which thermostatic circuit controlling devices of the kind having a movin arm operable upon the expansion. of a tu e for the purpose of flexing such arm and thereby operating contacts which control the opening or closing of circuits which thereupon actuate switch devices for operating signal circuits and local alarm circuits.

The present invention provides an improved construction of thermostatic circuit controlling device that will ensure reliable. .action thereof enabling such device to func tion with either a double closed main circu t system or a closed and open main c rcuit system.

The invention will be fully described with the aid of the accompanying drawings and diagrams, wherein Figure 1 is a side elevation of the thermostat in applied position.

Figure 2 is a longitudinal sectional view of the thermostat.

Figure 3 is an enlarged end elevation with the front cover cap removed.

Figure 4 is a sectional view of line 4-4 Figure 2, showing the thermostat arranged for a double closed circuit system.

Figure 5'is an end elevation corresponding to Figure 3 but showing the blades in contact arranged for a closed and open circuit system.

Figure Figure 4.

Figure 7 is a sectional view on line 77 of Figure fi.

Figure 8 is an end elevation similar to Figures 3 and 5 but showing the contacts arranged in slightly different relationship to the circuit breaker.

Figure 9 is an enlarged sectional view of the end portion of thethermostat.

Figure 10 is a view of a portion of such thermostat.

Figure 11 is a diagram showing the wiring when a closed and open circuit system is used.

Figure 12 is a diagram when the arrangement shown in Figure 8 is used.

Having more particular reference to the 60 drawings wherein like characters of refer- 6 is a sectional elevation similar to once will designate corresponding parts, throughout, the thermostatic switch or circuit closer, whereby the various circuits of the fire alarm system may be selectively opened and closed, consists ofa case 1 whic has a flange 2 between which and a nipple 3 .is arranged. an insulating washer 4 thereby insulating the thermostatic switch from the nipple 3 that is directly connected to the conduit 5 which receives the various electric 50 wires and which is usually concealed in the ceiling or wall of the building. A central web 6 of the casing has the expansion tube 7 threaded into anipple 8 projecting from one side of the web. On the other side of the 5 web in a-recess is an insulating plug 9 that supports posts 10 and 11, a leaf spring contact 12 being connected to'the post 10 and a similar contact 13 connected to the post 11. The contacts 12 and 13 are in the form of yieldable strips with the contact 12 normally engaging an adjustable contact screw 15 mounted in a post 16. A post 17 carries an adjustable contact screw 18, which, in Figure 3, has the contact 13 under its own tension 76 normally held in engagement with it, but which, in Figure 5, and Figure 8, has the contact 13 normally held out of engagement with it by an adjusting screw 19 passing through a. post 20. The movement of the go contacts 12 and 13 for making and breaking the circuits is controlled by contact making rod 21, the flexing of which is thermostatically actuated b the tube 7. The end of this rod 21 projects t rough the web 6 and insulats5 ing plug 9, and is. carried centrally through a tube 22, slightly spaced from the tube 7 and is fixed to a head 23 of a tubular member 24, the rear end of which is fixed inthe end of the tube 22, the central portion oi the so tubular member being reduced so as to leave only a lateral wall 25 having a certain amount of flexibility. On actuation, a stem 26 beug threaded into anut 27 directly threaded into the end of the tube 7 passes through he tube 24 and has its point end lyingin a recessed part 28 on the head to establish a direct action betweenthe rod 21 and the tube 7 thereby regulating the flexing of the wall 25 and displacement of the rod 21 according to inner tube,

the tu being squared as indicated at 28 ment with a suitable tool, whereby the stem may be turned for moving the point end towards and away from the recess 28.

The tube 22 has one end rigidly connected with the end of the threaded into the nipple by being expanded and forced into the end of such outer tube,

while the member 24 may be secured to the end of the tube 22 by being forced therein.

As the tubular member 24 is fixed to the end of the tube 22, the stem 26 is adjusted to create sufiicient pressure against the head 23 i to fiex the lateral wall 25. and it will be seen that the rod 21 is forcibly held to one side of the centre of the tube, as suggested in Figures 3, 5 and 6. r

With elongation of the tube 7 through expansion when subjected to heat, it will move the stem 26 slightlyaway from the recess 28 thereby allowing the flexibility of the lateral wall 25 to move the rod 21 away from its normal position and to operate the contacts 12- and 13, as will hereinafter be explained.

It is important to note that the outer tube 7 is arranged concentrically of the inner tube 22 and in slightly spaced relation thereto, completely enclosing the stem with an intervening air space 31 with the result that the sudden rise in temperature will cause the.

outer tube to expand independently of the but should there be agradual rise in temperature the heat will pass throu h the outer tube and act upon the inner tu e in the same proportion, thereby allowing the inner tube and outer tube to expand uniformly and thereby accomplishing a compensating action to prevent the flexing of the rod and consequent operation of a thermostatic switch.

The outer surface of the tube is preferably spirally fluted as at 30, the thinning of the tube also allowing a greater amount of surface to be presented to the heat and the expansion thereof is hastened, but the strength of the tube is retained. 7

Supported by the case. 1 is an insert 32 of insulating material which carries the terminal connections 33 which are connected to theposts 10 and 11 which carry the blades 12 and 13. A terminal screw 34 is also provided for connecting a conductor or conductors to which is earthed some of the contacts. In Figures 2, 3 and 4, the post 16 is screwed into the insulating plug 9, while a terminal pin 35 from a plate 35a under the post 16 passes through the plug 9 and insert 32, the pin 35 passing through a hole of larger diameter in the web 6 in the same way as the posts 10 and 11 in. Figure 7 while the post 17 is screwed into the web 6 and thus earthed to the terminal 34. In Figures 5 and 8, both posts 16 and 17 are carried by the insulating outer tube, which is plug 9 and so are insulated from the terminal 34 which is, in this case, earthed to the rod 21.

A cap 35 screws on the end of the case 1 so that ready access to the contacts is allowed,

while a plate 36 is held in place by a bolt 37 and enables access to be obtained to the terminal connections.

Fine adjustment of the contacts against which bears the closed circuitleaf 12 may be obtained by a fine thread on the contact 15, while a projecting rim 38 (see Figure 5) is marked into a number of equal spaces registering against a mark on the post 16, each space indicating the exact distance the screw has moved forward upon being rotated such a distance. A plate 39 connecting the posts 16 and 18 in the form shown in Figures 5 and 8 makes these two contacts electrically one.

The circuits and the operation of the device Will now be described with reference to the diagrams.

Referring to Figure 11, showing a diagram of the circuits when combined closed and open circuits are used in the main alarm circuits, in such a case the blades and contacts are set as shown in Figure 5. In this figure the end of the arm 21 forms a contact earthed to terminal 34 as before described and normally bears against the blade 12, retaining the blade in engagement with the contact 15, so that when the red the blade 12, the tension of such blade will cause it to move from the contact 15 and break any circuit therethrough. The normally closed main circuit includes a conductor 100 indicated by thick lines leading from a source of current, such as the' battery 102. In the circuit is included the contacts 55 and 56 and the coil 53 of drop switch 47. Such conductor 100 leads to the post 10 which carries the blade 12 normally bearing on the contact 15, while another conductor 103 leads from the contact 21 back to the other pole of the battery 102.

A normally open circuit consists of a conductor 104 leading from one pole of a battery 105 and passes through contacts 69-70 and coils 67 of the open circuit switch 62, and is then divided into two lines indicated as 104 and 104a following the conductors 100 and 103, and is connected to the posts lland the blades 13. The action of these two circuits is as follows Upon heating of the tube 7, the rod 21 will be caused to move laterally as hereinbefore described, and will move away from the blade 12 and break its engagement with contact 15, thus breaking the closed circuit along the conductors 100 and 103, and this breaking immediately de-energizes the coil 53 of the drop switch 47 which will then fall, causing the pins 61 associated in any suitable known manner with said switch to bridge 21 moves away fromhaving been so bridged, enables other con-' the sets of contacts 57 and 59. These contacts tacts to be completed, for example, a buz zer circuit not shown, for indicatin a warning" in any particular part of the uilding.

Further heating of the tube 7 causes the rod 21 to still further flex laterally until its end engages the blade 13. When this happens, the open circuit is completed from the battery 105 along conductor 103, blade 13, along the two branches 104 and 104a energizing the coil 67. Immediately, however, such circuit is formed the energization of the coil 67 will cause th fall. Should, however, line 103 be broken, such circuit will not be completed. In this case, the rod will continue moving until it carries contact contact 18 and the open circuit is then comleted from battery 105 or 106 along a conductor 108 through a set of contacts 57 and 59 by a pin 61 to conductor 100, to blade 12, then through bridge 39 to blade 13, to wires 104 and 104a, thereby causing the switch 62 to drop. The pins 74 bridge the contacts 75 and 76, which may close other circuits as follows A signal circuit 109 for operating the transmitter 110, the circuit of which is from battery 111 through contacts of both switches, so that before t e transmitter is operated both switches must fall. Wires 121, 122 and 123 enable the transmitter to operate from battery 102 should battery 111 fail.

A street bell 114 from battery 106 is also operated when both switches are down, the circuit of which can be easily traced through the contacts.

Anannunciator 116 may also be employed which is operated when the switch 62 falls,

the coil of such annunciator being inserted in the open circuit line and having another conductor 117 tapped thereto which leads to a contact 7 of a'set, and from the contact 75 of such set anotherconductor 118 is tapped to the line 104. The resistance of the coil 67 is such that only a small amount of the currentfrom the battery will pass through it and annunciator 116 when the open circuit is completed, but immediately the switch arm 62 falls, closing the sets of contacts 75 and 76 and breaking the contacts 69 and 70, all the current from the battery 105 will pass through annunciator coil 116 by means of the lines 117 and 118, and thus operate the.

annunciator.

Another circuit is formed by a conductor 119 from contact 69 to a set of contacts 57 and 59, and thence through the contacts 71 and 72, and from contact 72 to battery 106 by conductor 120, and this circuit, after the closed circuit switch 47 has fallen, but before the open circuit switch 62 falls, forms an auxiliary circuit from battery 106 in case the e drop switch 62 to.

blade 13 to engagement with Figure 3, and first touches the blade 12,

breaking the closed circuit, and moves the blade 12 until such blade touchesa contact 78 on the blade 13, thus closing the open circuit from conductor 100 to line 104 or 104a i through the blade 13. If such line is broken,

then when the blade 13 touches the contact 18 a circuit is completed from conductor 103 through the bridge 39, contact 18 and blade 13 to lines 104 or 104a. a

The contacts of the device, such as contact 78, end of rod 21 when used as a contact, and other contacts, may be of silver to make them reliable and sensitive.

What we claim is 1. In a thermostatic switch device having a group of contacts, a circuit closer for selective engagement with said contacts, a readily expansible tube, an actuatorassociated with the tube and having an operative engagement with said circuit closer, whereby upon expansion of said tube due to heat, such circuit closer will flex laterally to operate selected contacts of said group of contacts for co-operation with the other contacts of such group for opening or closing main circuits through such thermostatic switch.

2. In a thermostatic switch device having a group of yieldable contacts, fixed contacts associated with said yieldable contacts, an outer tube having one end fixed in relation to fixed to the outer tube, a rod mounted in said inner tube for moving into and out of engage ment with said yieldable contacts, an actuator mounted in the outer tube and having operative engagement with said rod for flexing the same when subject to certain degrees of heat in order to operate said yieldable contacts in relation to said fixed contacts.

3. In a thermostatic switch having a group of yieldable contacts adapted to engage other contacts, an outer tube having one end fixed in relation to said contacts, an inner tube fixed to said fixed end of said outer tube having free relative movement to each other, a tubular member within said inner tube and fixed thereto at its free end, a flexible portion in such member, a circuit closing rod fixed in said member forward of said flexible portion,

an actuating stem adjustably connected to the end of said outer tube, and bearing against a part of said tubular member behind the rod to control the flexing of said rod, upon expansion and contraction of said outer tube. as claimed in claim 2, sald' PO A IOU

retained against a fixed contact, but on being flexed laterally will move from said yieldable contacts and engage said other yieldable contact completing a circuit therethrough and further movement of said rod will cause said other yieldable contact to engage another fixed contact completing a circuit from such other yieldable contact to the first fixed contact, substantially as described.

5. In the device as claimed in claim 2, said I yieldable contacts arranged laterally to said rod, which on being flexed will first disengage one of said yicldable contacts from a fixed contact, and further movement thereof will cause said yieldable contact to engage a second yieldable contact which is thereby moved until it engages a second fixed contact, substantially as described.

6. In the device as claimed in claim 2, said inner and outer tubes arranged in slight spaced relation, this providing an air space forpermitting the expansion of the outer tube for flexing said rod upon sudden heating but permitting both tubes to expand upon a slow heating, whereby the rod is not operatively flexed.

In testimony whereof, we have signed our names to this specification.

THOMAS STOKER DIXON. ALBERT EDWARD SIMPSON. 

